The present invention relates to a spherical sealing body used for exhaust pipe joints and a manufacturing method thereof.
An axhaust gas of automobile engine is led through an exhaust pipe disposed on a car body frame or the like from the engine and discharged into the atmosphere, however, the exhaust pipe is subjected to a repetitive bending stress due to torque reaction force of the engine, force of inertia and so forth. Particularly in the case of front wheel drive engine arranged transversely, the bending stress grows heavy as compared with that of the engine arranged longitudinally.
Accordingly, vibrations of the engine will be brought into a car room (to fill with a sound) along an exhaust pipe suspension, or not only thus a noise is caused thereby but also a fatigue fracture is capable of resulting on the exhaust pipe.
To solve such problem, a means has been taken such that a spherical pipe joint is disposed at a predetermined position of the exhaust pipe to absorb the stress.
A spherical sealing member has been used for conventional spherical pipe joints, and a function to allow smoothly a relative angular motion between two of the exhaust pipes arising according as the automobile engine rotates, a sealing function to prevent leakage of an exhaust gas from a pipe joint portion, a function to absorb infinitesimal vibrations of the exhaust pipe arising according as the automobile engine rotates and so forth are required for the spherical sealing member.
As disclosed, for example, in Japanese Patent Publication (kokoku) No. 58-21144, that for which a wire mesh and a sheet-like refractory material (expanded graphite sheet, mica sheet or the like) are laminated with each other, wound cylindrically to obtain a preform body, and then the preform body which is compressed axially thereof has been used so far as the spherical sealing member.
The above-described sealing member consisting of a wire mesh and a refractory material has an integrity in structure such that the refractory material is filled thoroughly in the wire mesh and clearance and thus both are entangled with each other in order, and the refractory material exposed on a convex spherical surface of the sealing member is provided with a flexibility itself and hence is fittable well to the mating surface, therefore a sealing function to the leakage of an exhaust gas at the spherical joint portion is enhanced, however, since the sealing member itself works as a rigid body to infinitesimal vibrations arising on the exhaust pipe, an absorbability of the vibrations can hardly be expected, thus leaving the problem of generation of a noise due to the vibrations and a sound filled in a car room.